BBO crystal growth development during utilization of the heat field rotation method

Abstract

In the last one and a half decade crystals of barium metaborate (β-BaB2O4 or BBO) have been widely applied in non-linear optics and electro-optics. The growth of BBO is a technologically sophisticated procedure enabling the production of big high-quality single crystals. The best results have been obtained by growing BBO with top-seeded solution growth (TSSG) method in the BaO-B2O3-Na2O ternary system. The typical effect of constitutional supercooling results from a high viscosity of the melt-solution and the fact that a growing BBO crystal shields the crystallizing melt, thus weakening convective flows and removing heat away from crystallization interface. The contribution considers the possibility of the improvement of crystal growth process via the change of heat field symmetry and its rotation. Such the nonconventional approach has allowed to carry out the contact free structurization and intensification of convective flows in the melt-solution body and by that to reach more complete crystallization of a material increasing the yield before effect of constitutional supercooling. In that way we grow BBO crystals, from which it is possible to make non-linear optical elements of 15x15x15 mm3 sizes and electro-optical elements for Pockels cell with 6x6x22 mm3 sizes along an optical axis.